Module A-137-2 is another version of a wave
multiplier. In contrast to the A-137-1 Wavemultiplier I
the A-137-2 generates four phase-shifted copies of a VCO signal applied to the
audio input. The four shifted signals are added to the original signal to obtain
a fat sound similar to five independent VCOs. The phase shifting is made by a
simple circuit that works only for sloped signals like sawtooth, triangle or
sine, but not for rectangles or pulses:

schematics (one
unit)

Working
principle: The audio input
signal (typically a sawtooth, triangle or sine wave from a VCO) is
compared with a slowly varying control voltage (CV Shift In). The output
of the comparator is a rectangle wave with variable pulsewidth. When the
output of the comparatur is added to the input signal (a sawtooth in the
example) with the correct level relation between both signals one obtains
a phase shifted sawtooth. The left picture shows the incoming sawtooth
wave on top. The two horizontal dashed lines (blue and orange) indicate
two different comparison levels. Below the incoming sawtooth the two
resulting comparator outputs (rectangle waves) and the two resulting
shifted sawtooth waves are shown. It is not a "real" phase shift but
an algebraic function. But the result is virtually the same. One could
obtain the same function even with several comparator modules A-167
and mixers A-138a/b or polarizing mixers A-138c.
But this would require a lot of modules.

The module has available four
manual shift controls and four control voltage
inputs with attenuators for the four internal shifting circuits. Typical sources
for these inputs are LFOs, VCLFOs, random voltages, envelope generators,
sequencers or other control voltage sources. Internally eight single outputs are
available at single pins: the four shifted signals and in addition four
rectangle outputs. A corresponding breakout module with eight sockets is in the
planning stage and will be released provided that there are sufficient
inquiries. The original signal and the four shifted signals are equipped with
internal jumpers. If external toggle switches are used instead of the jumpers
each of the 5 signals can be turned on/off individually.

The audio input is equipped with an attenuator to
adjust the level for the right summation of the original and the comparator
signals (as described above).

schematics (complete
module)

This document shows the positions of
the five jumpers and the eight single outputs on the pc board:
A137_2_appendix.pdf

For these examples an sequencer (A-155)
was used to generate the CV for both the VCO and the LFO. The sine output of the
voltage controlled quadrature LFO A-143-9 was connected
to CV Shift 1 of the A-137-2. An ADSR (A-140) and
VCA (A-131) was used to texture the boring pure sound. In
the first example the sawtooth output of the VCO is used, in the second example
the triangle. Both examples start with CV Shift 1 set to zero. Then the
level is increased. After a while the manual frequency control of the Quadrature
LFO A-149-9 is chanched. In the second example the frequency of the LFO A-143-9
is switched into the audio range at the end of the example.

In the next example the same ADSR that controls the VCA
loudness is used to control the shift too. The second output of the ADSR (A-140)
is connected to CV Shift 1 of the A-137-2.
For clarity again only one shifting stage is used: